The present invention relates generally to internal combustion engines and, more specifically, to an internal combustion barrel-style engine with an integral air compressor.
Barrel engine configurations have conventionally held the potential for high power density packages. This is desirable in many applications, particularly those requiring mobile power sources such as automotive and truck markets as well as aerial vehicles. Barrel engines typically involve a grouping of power cylinders and pistons that are oriented such that their axes are parallel to each other as well as the power output shaft. Power is transmitted from the reciprocating pistons to a cam plate via a roller interface. The cam plate""s nominal plane is perpendicular to the piston axes and attached to the output shaft. One variation, commonly referred to as a double-ended barrel engine, typically uses a double-ended piston construction and utilizes pistons that have power cylinders at each end. Another configuration of the barrel engine concept, commonly known as a single-ended barrel engine, only uses power cylinders on one end of the piston and is commonly known as a single-ended piston construction.
In either case, a significant challenge is the ability to react side loads on the pistons caused by the pressure angle of the cam surface. This side load must be reacted on both sides of the cam and piston interface and may involve use of crosshead devices or the piston skirt(s) directly. Double-ended piston configurations have an advantage in this area in that the double-ended piston configuration naturally lends itself to improved reaction of the piston side loads.
The present invention provides an improved barrel engine with an integral air compressor. The engine is fundamentally a single-ended barrel engine that utilizes a double-ended design wherein one end of the engine is used for combustion, while the other end is used to compress air and act as a supercharger. The two ends are preferably interconnected such that compressed air from the compression end is fed to the intake system for the combustion end, although it is possible to use the compression end for other purposes such as gas compression. In one embodiment, the internal combustion barrel engine includes an output shaft with a longitudinal central axis that is rotatable about the central axis. A first combustion cylinder and a first compression cylinder are spaced apart and disposed on a common cylinder axis that is generally parallel to the central axis. The cylinders each have a inner end and an outer end, with the inner ends being closer to each other. An intake system is operable to introduce a combustible mixture into the combustion cylinder. A combustion piston is moveable within the first combustion cylinder and operable to compress the mixture in the combustion cylinder. A compression piston is moveable within the first compression cylinder. A track is supported on the output shaft and extends generally radially therefrom, such that a portion of the track is disposed between the inner ends of the first combustion cylinder and the first compression cylinder. The track has a longitudinally undulating surface and is rotatable with the output shaft such that as the track and output shaft rotate, the portion of the surface most directly between the inner ends of the cylinders undulates toward and away from the inner ends of the cylinders. A connecting rod has one end connected to the combustion piston and another end connected to the compression piston. A mid-portion of the connecting rod is in mechanical communication with the surface of the track such that as the track rotates the connecting rod urges the combustion piston outwardly within the first combustion cylinder to compress the mixture and then allows the combustion piston to move inwardly as the mixture expands. The compression piston moves with the connecting rod such that as the combustion piston moves outwardly, the compression piston moves inwardly and as the combustion piston moves inwardly, the compression piston moves outwardly. A valve assembly is provided to provide ambient air to the compression cylinder and to vent compressed air from the compression cylinder. The valve assembly comprises a generally flat valve plate having a generally flat inner surface facing the compression piston and an opposed generally flat outer surface. The valve plate further has an intake passage and an exhaust passage defined therethrough in fluid communication with the compression cylinder. An intake flapper valve is disposed on the inner surface of the valve plate and has a first position wherein the intake flapper valve is adjacent the inner surface of the valve plate and covers the intake passage. The intake flapper valve has a second position wherein a portion of the intake flapper valve flexes away from the inner surface so as to uncover the intake passage. An exhaust flapper valve is disposed on the outer surface of the valve plate and has a first position wherein the exhaust flapper valve is adjacent the outer surface of the valve plate and covers the exhaust passage. The exhaust flapper valve also has a second position wherein a portion of the exhaust flapper valve flexes away from the outer surface so as to uncover the exhaust passage. The compression piston and the first of the compression cylinders cooperate to compress a gas.
In further embodiments, a compression plenum is provided in fluid communication with the exhaust passage, such that compressed air from the compression cylinder flows into the compression plenum. The compression plenum is also in fluid communication with the intake system such that the intake system is operable to introduce a compressed combustible mixture into the combustion cylinder. A wastegate may be provided in fluid communication with a compression plenum and be selectively operable to vent the compressed air from the compression plenum. In other embodiments, the valve plate may include second and/or third or more intake and/or exhaust passages defined therethrough so as to increase the flow of gas into and out of the compression cylinder. When additional passages are provided, the same intake and exhaust flapper valves may be operable to cover and uncover these additional passages. In yet another embodiment, first and second compression and combustion cylinders are provided, along with first and second combustion and compression pistons, and first and second connecting rods. In this multi-cylinder embodiment, a compression plenum may be provided in fluid communication with the exhaust passages from each of the first and second compression cylinders. This compression plenum may then, in turn, be in fluid communication with the intake system for the combustion cylinders. Again, a wastegate may be provided for venting the compression plenum.